This specific piece of correspondence may be found on Joshua
Lederberg's NLM website, identified with the ID:
bbacqq.
http://profiles.NLM.NIH.gov/BB/
This document establishes that Joshua Lederberg was under contract to do research at Camp Detrick. This document also discusses mutagenic agents, likely to be used in the Biological Warfare sections of Camp Detrick. Other documents on this website make it clear that the correspondence is with researchers at the Biological Warfare sections of Camp Detrick.